Restriction-Modification (R-M) systems comprise pairs of opposing intracellular enzyme activities, a site-specific endodeoxyribonuclease (ENase), and a DNA-methyltransferase (MTase). Restriction endonucleases, derive their name from a host-controlled phenomenon of restriction and modification. Characteristics of R-M System MTase modifies DNA by methylation (Figure 3), protecting the cell’s own DNA from cleavage by the restriction enzyme. They recognize … Read More